Field
This field is generally related to dental instruments.
Related Art
Intraoral mirrors, also known as mouth mirrors, are among the most functional and frequently used of dental instruments. Viewing objects in a mouth directly is difficult due to a limited, or perhaps nonexistent, line of sight. Intraoral mirrors allow a health care provider (HCP), for example dentist, hygienist and others, to indirectly view teeth and other objects in a patient's mouth, such as the patient's gums and tongue, by observing their reflections in a mirror. Health care providers use the intraoral mirror for a variety of tasks, including, but not limited to, evaluation and diagnosis, treatment selection, and even to assist the treatment itself. A health care provider may use other tools, such as a dental hand piece, in conjunction with the mirror to conduct procedures, such as tooth preparation, when the procedures are conducted in areas that are not directly visible.
Not only are they used as a visual aid, intraoral mirrors are also used as rigid tools to manipulate or protect objects in a patient's mouth. For example, a health care provider may use an intraoral mirror to shift a patient's cheek to make space for treatment or to expand the mouth space for improved visibility. In addition, an intraoral mirror can protect soft and hard tissue structures of a patient's mouth while other parts of the mouth are treated.
Since an intraoral mirror is in contact with a patient's tissues inside their mouth, the mirror goes through sterilization after each treatment. In some cases, sterilization is done using a process known as “autoclaving.” Autoclaving subjects the mirror to high temperature and pressure, perhaps using steam. Because the mirror must be sterilized after each treatment, a dental office possesses multiple such mirrors. The mirror, made mostly of glass and metal, can withstand the autoclaving process. But, due to frequent use and sterilization, the mirror eventually loses some of its clarity and its reflectiveness, thus needing replacement.
In addition to intraoral mirrors, intraoral cameras are becoming more widespread in dental clinics. Intraoral cameras have principally two uses. First, intraoral cameras are used to describe a diagnosis and explain a possible treatment to a patient. For example, to explain a diagnosis or treatment, the health care provider may display images of the patient's mouth parts (e.g. teeth) to the patient. Second, the intraoral cameras are used to record the state of portions of the patient's mouth. For example, a health care provider may capture a photographic image of the patient's mouth before or after treatment.
Intraoral cameras are commonly shaped as pens, with an image capture device at their tip, pointed sideways. The tip helps orient the HCP as to where to position the camera to capture images of the desired area of the mouth. The captured images are presented in a display, and the navigation is done using the display. However, because these displays are the only viewfinder for the cameras, their use adds time to a dental appointment. Additionally, in a common usage scenario, heath care providers would commence a mouth inspection using a mouth mirror, if a need to capture an image arises, the HCP would have to switch the intraoral mirror with an intraoral camera. This may seem a minor hassle, but in the busy environment of a dental clinic, it reduces the frequency of capturing images.
Some dental procedures use dental composite resin material to glue fillings or build up structures on teeth during restoration procedures. After applying the material it is hardened using an instrument called a light cure. The light cure is used to illuminate the resin with light within the spectrum of visible blue to ultraviolet. This light might be harmful to the eye, therefore an eye protector is used by the healthcare provider while using the light cure. To perform such procedure, a health care provider applies the resin to the teeth. In many cases, to observe the tooth of interest, a health care provider uses a mouth mirror while applying the resin. When done, the health care provider switches instrument to a light cure, and illuminates the area for the resin to cure. When building up material on a tooth, the process repeats so that resin is applied, followed by curing, and then applied again, requiring to repeatedly switch the mouth mirror and light cure instruments.
During a typical patient visit to a dental office, a health care provider will record the patient's current dental status, also known as a dental tooth charting. A dental status, or dental tooth chart, is a diagram depicting the human teeth, where each tooth in the diagram is marked to indicate an aspect of the tooth's condition. In examples, a marking may indicate that a tooth is missing, has had dental treatment in the past, has a carious lesion, or has periodontal disease. Such status is updated from time to time to reflect the patient's most up to date condition. By inspecting the diagram, a health care provider (HCP) may become quickly informed about a patient's dental health status.
Like other medical professions, dentists need to track their work by recording and archiving with particularity a patient's dental condition and treatments. To facilitate such recording and archiving, computerized medical record systems exist. Generally, before adding or modifying data in an archive, a health care provider logs into the system to identify herself as the person providing the treatment. After logging in, the health care provider can select a patient record to retrieve information on file or to add additional information to the patient's record, such as a description of the current procedure, progress, and diagnoses for future treatment. The information in the patient's record is mostly text. Images might also be recorded, but the accompanying text is essential for the record. Therefore, the input regarding the treatment usually occurs at its end, when the professional is able to freely use the computer keyboard, both for convenience and for proper hygiene. Some of these computerized medical record systems include a digital version of a current status diagram, graphically depicting each tooth with a variety of marks and colors to represent various conditions.
Entering data into a patient's medical record takes time. However, in operating a dental office, efficiency is important. Less time spent on administrative tasks leaves more time for treatment. One of the hallmarks of a well-managed clinic is how efficiently time is used. As a result, some dentists, despite having implemented a computerized system as a management tool for their dental office, avoid the step of entering a textual description of the session to the system, and keep handwritten notes instead.
In dentistry (including orthodontics), multiple procedures exist that require generating a three-dimensional (3D) model of a patient's mouth. At present, many of these models are created using physical material, such as the routine use of plaster models. Recently, technologies and products have emerged for the creation of a digital representation of the 3D modeling, the models commonly called “digital impressions.” These various products vary in the accuracy of the digital 3D model they achieve and in the amount of time that a dentist (or other dental health care provider) has to spend during the dedicated scanning session.
The general structure of 3D scanning machines consists of a scanning head, which performs intraoral measurements, from which depth measures can be extracted (calculated), and connected to a computer unit which processes the measurements to produce a digital model. The creation of a 3D imprint of the mouth is necessarily performed in a dedicated session, during a time period allocated specifically for this task.
The computing resources, such as processor and memory capacity, needed to produce an imprint are substantial. The acquisition of depth measurements is done in sections, the size of each of the sections is determined according to the amount of concurrent depth information that can be acquired by the scanning head. Then, generally, a 3D model of that section is calculated. Later, a registration of the various sections is performed, to allow the “stitching” of adjacent digitized regions into one consistent model. Additionally, if colors are acquired, a process of coloring and of possibly adding texture is performed. Additional processes might also be employed. The computer processing power required to produce such digital imprint in a reasonable amount of time is, therefore, substantial.
The technology implemented in the scanner head affects both accuracy and speed. The simplest of these, at least when being measured in terms of availability of electronic components, is a scanner head with an image capturing camera.
Several algorithms for extracting depth information from sets of images exist, involving identification of matching points or shading extraction or other concepts, followed by solving a so-called “triangulation problem”.
In practice, achieving accurate depth measurements through image analysis in a short period of time is challenging since much of the information that is extracted from images tends to exhibit geometric noise, due to either distortion in the image capturing process, or uneven reflection of the illumination of intraoral objects. One of the reasons for the presence of such uneven illumination is that some areas may exhibit Lambertian reflection, while other areas exhibit specular reflection. The presence of saliva in an intraoral environment, is an additional, and sometimes substantial hurdle to the accuracy of the process, since it may cause some areas to exhibit specular reflection even if otherwise they would not. Using a multitude of captured images of an intraoral object from various angles, will greatly assist the triangulation accuracy, but unfortunately will extend the computational effort and hence the amount of time and processing power required for accurate calculation.
Systems and methods are needed to provide a more efficient way to show a patient images from the patient's mouth, to record the patient's dental status, and to create digital dental impressions.